Influence of diluents and solvent on stability of water dispersion of poly(vinyl chloride)
– plastisol dispersion
Polimery 2007, No 11/12, 863
Sedimentation, viscometric and rheological investigations of aqueous dispersions of PVC plastisols were presented. These plastisols contained three various plasticizers and were stabilized with ethoxylated saturated fatty acid ("Rokanol Ł 18"). Some amounts of organic diluents and solvent were introduced into the dispersions. The following plasticizers were used: dibutyl phthalate, di(2-ethylhexyl) phthalate and dibutyl sebacate. Xylene, n-butyl acetate, and butanol were used as diluents and cyclohexanone was used as a solvent. At the sedimentation equilibrium state aqueous dispersion of PVC plastisol was separated into three phases. The upper phase consisted of foamed PVC plastisol, the middle one was stable phase of PVC plastisol aqueous dispersion while the lower one costisted of homogeneous deposit of PVC plastisol. The middle phase was the subject of our investigations. PVC plastisol dispergation efficiency (Wd) and limiting viscosity number (GLL) of PVC plastisol were determined and rheological investigations were done. GLL calculated from Huggins equation let evaluate the particle size of PVC plastisol. Rheological tests allowed determining maximal viscosity and pseudoplastic factor from flow curve, using the modified Ostwald de Wael equation. Activation energy of viscous flow was calculated from Arrhenius-Guzman equation. The results obtained showed significant effects of the type and amount of diluent and solvent, introduced into PVC plastisol aqueous dispersion, on the process of particles' aggregation. Different way of particles' aggregation causes changes in dispergation efficiency, particle size and rheological parameters of the system. It was found that the most advantageous, from the practical application point of view, is an addition of a diluent or solvent in an amount of 0.0008 mole/g of plastisol. The mechanisms of the phenomena proceeding were explained by analysis of the values of miscibility coefficients of aqueous dispersion particular components.
Key words: PVC plastisol, aqueous dispersion, diluent, sedimentation, viscometry, rheological parameters
E. Makarewicz, K. Uziałło, K. Jańczak
Influence of diluents and solvent on stability of water dispersion of poly(vinyl chloride) - plastisol dispersion